Strapping tools of a type in widespread use are designed to tension the overlapped ends of a steel strap drawn from a supply and wrapped around a load, to punch interlockable shoulders into the overlapped ends of the steel strap and to cut one of the overlapped ends from any steel strap remaining in the supply, and to release the overlapped ends, so as to form a tensioned loop of the steel strap around the load. A steel strap having interlockable shoulders punched into its overlapped ends, as by a strapping tool of the type noted above, is exemplified in Tremper et al. U.S. Pat. No. 4,825,512.
Although as exemplified in Nix U.S. Pat. No. 5,136,888 many strapping tools of the type noted above are lever-actuated tools without pneumatic, electrical, or other motors, it is known for such strapping tools to be pneumatically powered and to have separate pneumatic motors controlled by manually controlled valves respectively for tensioning and for punching and cutting.
One concern with such a pneumatically powered strapping tool is that the respective pneumatic motors must be sequentially operated to form a tensioned loop. The pneumatic motor employed for tensioning must be energized for a sufficient time to tension the overlapped ends before the pneumatic motor employed for punching and cutting is energized. Otherwise, when the overlapped ends are released, the resultant loop may not be adequately tensioned and the overlapped ends may not interengage where punched.
Typically, however, the manually controlled valves controlling the respective pneumatic motors of such pneumatically powered strapping tools known heretofore can be independently controlled. Therefore, through inadvertence, a user may energize the pneumatic motor employed for punching and cutting before the pneumatic motor employed for tensioning has been energized for a sufficient time.